But nearly 100 million years ago relatives of modern snakes undulated through Cretaceous period waters aided by a paddlelike tail and dragging a pair of short, footless hind legs.
但是在将近1亿年前，现代蛇类的近亲们靠着它们船桨似的尾巴在白垩纪的水流里随波起伏，拖曳着它们短小而笨拙的后腿。
One of these designs has a pair of jet engines mounted aft, but positioned over and above the wing. This aircraft has no tail fins at all (see below).
其中一个设计方案有一对安装在尾部、在机翼上方的发动机，而根本没有尾翼（见下图）。
Larvae dark gray color, green or weak stomach abdomen only with three and a pair of tail foot.
幼虫深灰绿或淡青色，腹部仅有腹足三对及尾足一对。
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